Switching mechanism



Patented June 2, 1925.

UNITED STATES PATENT OFFICE.

OSCAR F. FORS'BERG, OF YONKERS, NEW YORK, ASSIGNOR TO WESTERN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SWITCHING MECHANISM.

Application filed December 28, 1922. Serial No. 609,378.

To all whom it may concern.

Be it known that I, Osoan F. 'Fonsnnno, a citizen of the United States,residing at Yonkers, in the county of cslchester, State of New York,have invented certain new and useful Improvements in SwitchingMechanisn'is, of which the following is a full, clear, concise, andexact'dcscription.

This invention relates to switching apparatus, and particularly to theso-called coordinating switch of the type employed in automatictelephone exchanges.

This invention is particularly applicable to a switching system ofthetype generally disclosed in the British patent to Western lillectricCompany, Limited, No. 183,338 of 1923, but it will be apparent tothoseskillcd in the art, that the invention may be applied equally wellto other switching systems.

Heretofore and particularly in the switch disclosed in the abovementioned"application, the practice has been' to have a rotata his linebar assigned to each group of incoming lines. Other' rotatable bars areas signed individually to link conductors, and still others to outgoinglines or trunks. The conjoint operation of one of each of these barseffects what is commonly known as a line-link-line connection. Therotatable bars assigned individually to link conductors are generallyprovided withpermanent- 1y mounted flexible fingers which cooperate withcamming surfaces associated with the link bars to effect the aforesaidconnections. The use of flexible fingers in a coordinate switch isgenerally disclosed in British Patent No. 213,437 of 1924, issued toVVester-n Electric Company, Limited. Inasmuch as these flexible fingersare constantly being distorted or tensioncd under the camming action ofthe line bar it has been found that in some cases these finger memberswear out and become inoperative. In other cases the lingers cut groovesin the cams, these grooves holding the wire fingers and preventing theirsliding over thecam surfaces.

It is, therefore, an object of this invention to overcome the aforesaiddifficulties in a. simple, economical switching structure of thecharacter described above.

This object is accomplished by pivoting the o 'ierating fingers on thehorizontal link bars and providing restoring springs therefor which,though acting to restore the pivotal fingers to normal subsequent totheir actuation, exert a negligible pressure on the free ends thereof asfar as the wear on the camming elements is concerned. The forcgoingresult is effected by placing the point at which the spring is made fastto a hori- Zontal bar as close to the pivotal point of its associatedoperating finger member as possible without nullifying its restoringeffeet. The force exerted by the spring on the finger members is adirect function of the finger member and varies from zero when thespring and finger members are parallel, to a maximum when the spring isat right angles to the finger member, assuming, as will be found inpractice, that the point at which the spring is made fast to the fingermember does not coincide with. the pivotal point of the finger member.It is therefore pparent that there exists a point'along the horizontalbar from which the spring will exert the least force in returning thefinger member to its normal position. The pivotal connection is capableof repeated operation for a very great length of time without showingany material signs of wear. Furthermore, the finger is shaped so as to0011 tact with and slide over the cam surface without the cuttingexperienced with the wire finger.

The invention will be readily understood from the following descriptionand by reference to the accompanying drawing in which F 1 shows a crosssectional plan view of a part of a coordinate switchen'ibodying thefeatures of this invention; Fig. 2 is a side elevation of the structureshown in Fig. 1 and viewed in the direction of the arrows shown at thedotted line; Fig. 3 is a view of an operating card employed in moving aset of active contacts into engagement with a set of passive contacts;Fig. at shows the particular form. of the operating linger member.

In the followingdescription like numerals designate the san'ie elementthroughout the several views and particular reference is made to- Fig.2.

Sets of active contacts 10 are shown partially embedded in a commoninsulating member 11 suitably held stationary in a switch frame notshown. Partially embedded in the member 11 and individual to each groupof active contacts 10 are spring members 12. The spring members 12 arefirmly secured to the pins which in turn cooperate with the eyelets 51in holding a retaining metallic plate member 52 in engagement with theinsulating member 11. At the free ends of each set of active contacts,one set of which includes contacts 1 1, and 16, and loosely mountedthereon, is an operating member or card 17 which is adapted to movevertically in a guide by the actuation of an associated spring member12. The card 17 is provided with a plurality of obliquely disposedapertures 18, 19 and 20 for the admission of the contacts 1%, 15 and 16,respectively, and at its lower end a triangular aperture 21 is providedto admit the spring member 12. The guides for the cards 17 (as seen inFig. 1) are formed by the superposition of a T shaped insulating member22 on the fiat rectangular element 23.

Coordinately disposed to the sets of active contacts 10 and interwovenbetween insulating members 2% are sets of passive contacts, one setcomprising contacts -5, 2G and 27 which in a switch of this type areknown as link conductors. For each group of link conductor sets orpassive cont-act sets there is provided a. horizontal operating bar 28which has pivotally mounted thereon an extending finger 29, there beingone such finger for each set of active contacts 10. The finger member 29is adapted to be brought into engagement with a corresponding springmember 12 to eti'ect the movement of a card 17 and the subsequentconnection between associated sets of active contacts 14:, 15 and 16 andpassive contacts 25, 26 and 27.

For each vertical row of active contacts 1 1, 15 and 16 there isprovided a vertical operating bar 30 which is provided with extendingcamming surfaces 31 adapted to cooperate with the free ends of thepivotal tingew 29 and position them in operable relation with the springmember 12. A vertical operating magnet 33 is provided for each verticaloperating bar 30 whereas each horizontal bar 28 is actuated by anindividual horizontal link magnet 32. The linger members, as shown inFig. 4, are provided with a substantially spoon shaped end portion, theconvex surface thereof acting as a bearing surface between the cammingmembers 31 and the finger members 29.

The following description of a complete cycle of operation of the switchwill give a clear understanding of the invention.

Assuming that a subscriber having access to the vertical line magnet 33initiates a call. The magnet 33 becomes energized and in attracting itsarmature 35 operates the member 36 which is rigidly mounted on the bar30, thereby efi'ecting rotation of this bar. The bar 30 in operatingmoves all of its associated camming surfaces 31. into operable relationwith their respective pivotal linger members 29. A horizontal linkmagnet 32 is then actuated and in attracting its armature 37, operatesthe member 38 which is rigidly mounted on the horizontal bar 28 (see topof Fig. 2 and right-hand portion of Fig. 1). The bar 28 thereuponrotates and the end of the pivotal linger 29 associated therewithengages a camming surface 31 and is thereupon forced into engagementwith a corresponding spring member 12. The

member 29 is provided with staggered pro jections forming a crotch tocatch and lift the spring 12. The upward movement of the member 29 istransmitted to the card 17 through the spring member 12. The card 17 inmoving upwardly in its guide brings the active contacts 14, 15 and 16into a wiping engz'igementwith the passive contacts 25, 26 and 27, thewiping efiect being accomplished by virtue of the oblique apertures 18,19 and 20 in the card 17. The camming action of member 31 causes theelement 29 to swing about a point 10 against the action of a restoringspring 41. Upon the completion ot a connection the magnets 32 and 33become deenergized, the vertical operating member-30 returning to normalunder the action of a restoring spring not shown. In like manner aspring 43 returns the horizontal bar 28 to normal subsequent to thedeenergization of magnet 32. \Vhen the horizontal bar 28 restores, thepivotal linger 29 disengages itself from the spring member 12 and isthen returned to its normal posit-ion by the action of its associatedrestoring spring ll. The card 17 and its associated set of activecontacts then return to normal condition.

It is to be noted that the maintenance of an established connection doesnot depend upon the continued energization of the vertical magnet 33 butthe connection is maintained as long as the horizontal link magnet 32remains energized. Furthermore, the fingers 29 are held operated freefrom any mechanical connection with the vertical bars on the camsthereon, so that the vertical bars may be repeatedly operated withoutdisturbing operated contact sets. In this manner the vertical magnet 33becomes accessible to other line-s in order to cooperate in establishingother connections.

lVhat is claimed is:

1. The combination in a switching mechanism of cooperating active andpassive contacts, a flexible element for supporting said activecontacts, said active contacts being normally out of engagement withsaid passive contacts, a pivoted device normally movable in a pathineffective to operate said active contacts, a bar for moving saiddevice, and another bar cooperating with said first bar for causing saiddevice to deviate from its normal path to engage said flexible elementto actuate said active contacts.

lot)

2. A switch comprising a passive contact, an active contact, a memberfor moving said active contact, flexible means for moving said member,cooperating bars, and means associated with said bars for operating saidmeans comprising a pivoted member mounted on one of said bars.

In a switching mechanism, the combination with cooperating operatingmembers of a cam associated with one of said members, an extendingfinger member associated with said cam, means for holding said fingermemberin engagement with said cam, an active contact, and a wire foroperatingsaid contact, said wire being adapted to be engaged by saidfinger member.

4. In a switching mechanism, the combination with cooperating operating.11161111 bers of a cam associated with one of said members, an extendingfinger member associated with the other of said members and cooperatingwith said cam, a spring ar ranged to hold said finger member inengagement with said cam with slight pressure, the pressure increasingnegligibly with any slight tension of the spring caused by the cammingaction of said cam, an active contact, and a spring wire for operatingsaid contact, said wire being adapted to be engaged by the said fingermember.

In witness whereof, I hereunto subscribe my name this 26th day ofDecember A. D.

OSCAR F. FORSBERG.

